Immunological Responses and Actin Dynamics in Macrophages Are Controlled by N-Cofilin but Are Independent from ADF

Dynamic changes in the actin cytoskeleton are essential for immune cell function and a number of immune deficiencies have been linked to mutations, which disturb the actin cytoskeleton. In macrophages and dendritic cells, actin remodelling is critical for motility, phagocytosis and antigen presentation, however the actin binding proteins, which control antigen presentation have been poorly characterized. Here we dissect the specific roles of the family of ADF/cofilin F-actin depolymerizing factors in macrophages and in local immune responses

Encuentros a través del espacio y categorías: ¿trabajadoras domésticas como hilo conector en la ciudad segregada?

This article analyzes the connections, encounters and exchanges that take place in and through the daily movements of domestic workers in Bogotá, Colombia. Specifically, it examines female employees’ relations and interactions in their places of residence, during transportation, in their places of work, and in other social contexts—micro-publics— to understand the extent and limits of segregation and exclusion, as well as resistances in women’s everyday practices. The ethnographic research shows household employees’ relative social isolation that is due to labor conditions and social distancing. The article contributes to discussions about urban inequalities and the right to the city.En este artículo se analizan las conexiones, encuentros e intercambios que tienen lugar en y durante los movimientos diarios de las trabajadoras domésticas en Bogotá, Colombia. En específico, se examinan las relaciones e interacciones de las trabajadoras en sus lugares de residencia, durante el transporte, en sus lugares de trabajo y en otros contextos sociales —micropúblicos— para comprender el alcance y los límites de la segregación y la exclusión, así como las resistencias en las prácticas cotidianas de las mujeres. La investigación etnográfica muestra el relativo aislamiento social de las trabajadoras domésticas debido a las condiciones laborales y el distanciamiento social. El artículo contribuye a los debates sobre las desigualdades urbanas y el derecho a la ciudad

La diáspora china: un acercamiento a la migración china en Colombia

The Chinese diaspora is the largest and most extensive among the world's migrant populations. Recent estimates put the number of Chinese emigrants at 40 million people. Far from being a homogenous group, members of the Chinese diaspora have diverse economic, cultural, social, educational, and personal backgrounds as well as very different life stories and emigration experiences. Despite the growing interest in the Pacific Rim and the constant immigration of Chinese to the Americas through the 20[th] century, there is very little information about their migration to Colombia. This article explores the topic from a historical point of view in order to fill this void. The little that is known about Chinese migrants to Colombia is presented in the context of a discussion on the diaspora in order to highlight the transnationality and multiplicity of identities among this migrant group. The article also examines the similarities and differences between Chinese migration to Colombia and other countries in Latin America and on other continents, relating these particularities to local contexts

La diáspora china: un acercamiento a la migración china en Colombia

La diáspora china es la más numerosa y la más extendida entre todas las poblaciones migrantes del mundo. Hoy se estima que el número de emigrantes ha llegado a los 40 millones. Lejos de ser un grupo homogéneo, los miembros de la diáspora china tienen distintos antecedentes económicos, culturales, sociales, educativos y personales, así como historias de vida y emigración muy diferentes. A pesar del creciente interés académico en la cuenca del Pacífico y en la constante inmigración china hacia América en el siglo XX, casi no existe información sobre los chinos en Colombia. El presente artículo ofrece un acercamiento al tema desde el punto de vista histórico, con el fin de llenar el vacío existente, poniendo lo poco que se sabe del tema en el contexto de la discusión sobre la diáspora, para enfatizar la transnacionalidad y la multiplicidad de identidades de este grupo de migrantes. Por otra parte, el artículo analiza las diferencias y similitudes entre la inmigración china en Colombia y la de otros países de América Latina y de otros continentes, relacionando esas particularidades con el contexto local

Ghettos on the Edge of the City? Social housing policy and social inequality in Colombia

Konfrontiert mit kontinuierlich wachsender Nachfrage nach preiswertem Wohnraum, begann die Regierung Kolumbiens in den 1980er Jahren mit einer neuen privatisierten Wohnungsbaupolitik, die Hauseigentümerschaft ermöglichen und fördern soll. Dazu wurden staatliche Subventionen und spezielle Hypotheken für die unteren Einkommensklassen geschaffen, sowie Preislimits und Steuerfreiabkommen für die privaten Baufirmen eingeführt. Besonders seit der Baukrise zu Beginn des Jahrtausends setzen private Konstruktionsfirmen auf den sozialen Wohnungsbau. Seitdem entstehen massenweise großflächige, standardisierte Wohnsiedlungen an den Rändern Bogotás. Bewohner_innen sind Niedrigverdiener_innen, die zuvor in informellen Siedlungen lebten. Für die staatlich subventionierten Hypotheken, mit denen sie sich einkaufen, müssen Käufer_innen ein festes Arbeitsverhältnis nachweisen, was die Hälfte der kolumbianischen Bevölkerung ausschließt. Basierend auf mit diversen Forschungsmethoden in neun verschiedenen Sozialwohnungsbaugebieten erhobenen Daten, analysieren wir in diesem Artikel die gegenwärtige Wohnungsbaupolitik Kolumbiens und ihre Folgen. Wir argumentieren, dass die neue Politik tatsächlich mehr Menschen Zugang zu Eigentumswohnungen verschafft. Gleichzeitig zeigen wir, dass ohne weiterreichende soziale Reformen die Gefahr besteht, dass sich die isoliert liegenden Wohnsiedlungen in urbane Ghettos verwandeln, die ihre Bewohner_innen weiterhin stigmatisieren. Zugang zu Bildung, Jobs, Kultur und anderen urbanen Ressourcen ist notwendig, um langfristige soziale Mobilität zu ermöglichen bzw. zu garantieren.Faced with a growing demand for affordable housing, in the 1980s the Colombian government embarked on a new, privatized housing policy designed to facilitate and promote homeownership. For this purpose, state subsidies and special mortgages for the lower income classes were created, as well as price limits and tax-exempt agreements for private construction companies. Especially since the economic crisis at the beginning of the millennium, private construction companies focus on social housing construction for profits. Since then, large-scale standardized housing estates have sprung up on the outskirts of Bogotá. Residents are low-income earners who previously lived in informal settlements. To access the state-subsidized mortgages, buyers must have permanent employment, which excludes half of the Colombian population. Based on multi-method collected research data in nine different social housing areas, in this article we analyze the current housing policy of Colombia and its consequences. We argue that the new policy actually gives more people access to condominiums. At the same time, we show that without further social reforms there is a risk that the isolated housing estates will turn into urban ghettos that continue to stigmatize their inhabitants. Access to education, jobs, culture and other urban resources is necessary to ensure long-term social mobility

Immunological responses of n-cofilin mutant dendritic cells.

<p>(A) Phagocytosis of FITC-labelled <i>E. coli</i> in n-cof^{flx/Δ,Mx1-cre}, ADF^-/-, ADF^+/-, and control macrophage cultures (n-cof^{wt/wt,Mx1-cre}); (B) Phagocytosis of FITC-zymosan by individual macrophages was scored (n_cells>100). Phagocytosis in ADF^−/− cells was not changed; (C) TNF-α production induced by Zymosan phagocytosis. Macrophages were allowed to ingest zymosan particles and after 16 hours, TNF-α levels were determined in the cell supernatant; (D-E) Impaired T-cell stimulation by n-cofilin mutant dendritic cells. Serial dilutions of OVA_323-339 peptide were presented by n-cof^{fwt/wt,Mx1-cre} or n-cof^{flx/Δ,Mx1-cre} dendritic cells to OT-II T-cells. T cell stimulation was measured by production of IL-2 (D) and IFN-γ (E) after 24 hours; (F-G) T-cell stimulation of ADF^−/− dendritic cells was similar to ADF^+/− controls; (H) MHC class II-induced contact formation is impaired in n-cof^null macrophages. A mix of control macrophages (escaper cells) and n-cof^null macrophages, preincubated with anti-MHC class II antibody were allowed to form contacts with the beads. Control cells form F-actin free contact zones (arrows) with anti-mouse-IgG-coated beads (FITC labeled, green), while n-cof^null macrophages showed a F-actin rich domain (phalloidin, red) at the interface with the bead (arrows).</p

<i>In vitro</i> and <i>in vivo</i> migration of macrophages lacking n-cofilin.

<p>(A) Random motility of n-cof^null BMM is impaired, ADF^−/− macrophages behave normally. Velocity of center movement over a period of 20 min is shown (n_cells>60, student's test n-cof^null:control p<0,0001); (B) Over a period of 8 hours n-cof^null cells show no significant net translocation, cell protrusions collapse back onto the cell body (see arrows). Migratory tracks are shown by white lines and dots, for two cells each (see also <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0036034#pone.0036034.s004" target="_blank">videos S1</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0036034#pone.0036034.s005" target="_blank">S2</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0036034#pone.0036034.s006" target="_blank">S3</a>); (C) <i>In vivo</i> recruitment of n-cof^null cells to sites of inflammation is impaired. Thioglycollate injection (TG) into n-cof^{flx/Δ,Mx1-cre} mice does not lead to recruitment of mutant macrophages (Δcof) to the peritoneum (PEC). N-cofilin depleted cells remain in the bone marrow (bm). Southern blot of the respective mutant cell fractions (n-cof^{flx/Δ,Mx1-cre}) is shown in the left panel, and the corresponding western blot in the right panel. PEC mainly consists of escaper cells as indicated by the equal Δcof/<i>flox</i>-cof signals in Southern blot and the presence of n-cofilin protein. Western blot analysis of control mice (n-cof^{wt/wt,Mx1-cre}), is shown on the right panel to illustrate the normal expression levels of n-cofilin in bm and PEC under these conditions; (D) FACS analysis of bone marrow (bm) and PEC from the experiment in (C). Bone marrow composition after TG injection (TG) and n-cofilin deletion (poly(I−C)+TG) was comparable (left panels). The main portion of bm cells were Mac1/Gr1 positive, few B cells (B220) and T cells (CD3) were detected. By FACS the Mac1 and Gr1 positive cells in bm appear as one population. 3 days after TG treatment, the majority of PECs in controls are positive for the macrophage marker Mac1 (upper right panel). Upon deletion of n-cofilin (poly(I−C)+TG), the PEC population increases in Gr1 (granulocytes) and decreases in Mac1 (macrophages).</p

Characterization of n-cofilin null macrophages.

<p>(A) Confocal sections through an adherent n-cof^null macrophage show the unusual cytoskeletal structure and the impaired leading edge formation. F-actin (in red) is shown by phalloidin staining. Note the short extensions emerging from the cell body and the lack of a lamellipodium; (B) Scanning EM of saponin extracted macrophages illustrate a loose network of short filaments in the lamellipodium of control cells, while n-cof^null BMM show densly packed cortical F-actin bundles; (C) Biochemical fractionation showed increased Triton X-100 stable F-actin levels in n-cof^{flx/Δ,Mx1-cre} macrophage cultures (n_culture = 6, p<0.05). ADF^−/− macrophages showed normal F-actin levels; (D) FACS overlay of phalloidin stained macrophages from a day 6 control (grey histogram) and n-cof^{flx/Δ,Mx1-cre} (black line histogram) culture. About 10-fold increase in phalloidin signal intensity was observed in n-cof^null cells, while the escaper cells are represented in the low intensity F-actin peak, similar to the control cells. (E) Cell adhesion on laminin is not altered in n-cofilin mutant macrophage cultures (n-cof^{flx/Δ,Mx1-cre}) at 4 to 24 hours after plating. The average of three independent experiments performed in quadruplicates is shown; (F) Cell spreading was significantly impaired in n-cofilin mutant macrophages (n-cof^null). The spreading area was compared in control (n-cof^{wt/wt,Mx1-cre}), ADF^-/-, ADF^+/− and n-cofilin mutant BMM (n_cells>100, student's test, n-cof^null:control p<0,0001; ADF^−/−:ADF^+/− p = 0,15); (G) N-cof^null BMM fail to polarize. The shape of more than 90% of n-cof^null BMM was apolar, while 75% of control and ADF^+/− cells were either bipolar or multipolar (n_cells>130). ADF^−/− BMM showed a noticeable tendency to increase cell polarization.</p